Field of the Invention
This invention relates to an image scanner for automatically scanning a document to optically read out and output image date that is on the document to an image processing device such as a computer, and more particularly to a portable image scanner capable of selectively uniting a cover member to a scanner body to feed a cut-sheet document to be scanned, or detaching the cover member from the scanner body to move the independent scanner body on a thick document such as a book.
Description of the Prior Art
Portable image scanners can be generally classified into a manually scanning type for manually moving the scanner along an image face of a document to be scanned, and an automatic scanning type for automatically moving a given document moved relative to the scanner to read out the image on the document. The portable automatic image scanner capable of scanning the whole image face of a given document is in widespread use for various image processing or optical character recognition (OCR), replacing hand scanners which are manually handled for scanning only a part of the image on the document.
The portable image scanners capable of automatically moving on the image face of the given document are further subdivided into 1 a document-feeding type portable scanner, generally called a "mannually document loading type scanner", capable of automatically feeding a cut-sheet document through a stationary scanner body to scan an image on the document, as proposed in U.S. Pat. No. 4,667,253, and U.S. Pat. No. 4,677,495; 2 a scanner-moving type portable scanner, generally called a "self-propelling type scanner", capable of moving along an image face on a fixed document so as to obtain image data directly even from a thick book, as described in U.S. Patent No. 5,182,450, Japanese Patent Application Public Disclosures Nos. SHO 61-251356(A) and SHO 63-42275(A) and Japanese Utility Model Appln. Public Disclosure No. SHO 58-127753(A); and 3 a combined type portable scanner having both functions of the aforesaid document-feeding type scanner and the self-propelling type scanner, as proposed in Japanese Patent Appln. Public Disclosures Nos. HEI 2-226958(A), HEI 2-22958(A), and HEI 4-117764(A).
The prior art combined type portable scanner capable of selectively feeding the cut-sheet document and moving on the fixed document has excellent applicability to various purposes, but tends to be complicated in structure and therefore is susceptible to mechanical trouble and awkward to handle.
For instance, the combined type portable scanner of Japanese Pat. Appln. Pub. Discl. No. HEI 2-22958(A) is composed of a combination of a detachable image reading unit and a document feeding unit. The image reading unit of this conventional scanner has a driving motor and a train of gears including a coupling gear, and the document feeding unit has a driving roller and a train of gears including a counterpart coupling gear to be engaged with the coupling gear of the image reading unit, so that which rotational motion produced by the motor in the image reading unit is transmitted to the driving roller through the gears including the coupling gears, so as to forward a cut-sheet document. However, the document feeding unit of this conventional scanner incorporating the driving gears becomes complicated in structure, and therefore, the scanner is unduly large and difficult to carry.
There has not been proposed so far a portable scanner with an automatic document feeder capable of automatically feeding a plurality of cut-sheet documents one by one in succession, even if it can automatically feed a single cut-sheet document. Thus, conventional portable scanners are inconvenient in handling a number of cut-sheet documents. Furthermore, since the conventional portable scanner uses an external power source in spite of its normal user with a handheld computer or the like, it is restricted in its use.
The conventional "self-propelling" type portable scanner capable of moving by itself on a fixed document such as a thick book to scan an image on the document must be manually stopped by giving a stop instruction from an external image processing device to the scanner or lifting up the scanner by hand when the scanner moving on the document arrives at the edge of the document. If an operator fails to stop the scanner, the scanner will fall from the edge of the thick document.